In the related art, technology for performing maintenance or management using an Ethernet (registered trademark) operations, administration and maintenance (OAM) frame in a packet transmission network is proposed (see Patent Document 1). In addition, in the packet transmission network, communication control such as flow control separate from the above-described maintenance or management is performed. In particular, flow control is generally used when it is necessary to construct an Ethernet (registered trademark) environment without packet loss such as a data center or a storage area network (SAN). When the flow control is performed in the packet transmission network, control is performed in units of physical ports, priority groups, or the like.
In the control in units of physical ports, the flow control is performed in units of physical ports as defined in Institute of Electrical and Electronics Engineers (IEEE) 802.3. Specifically, where a capacity sufficient to process traffic does not remain in a buffer of a reception side, a pause frame is transmitted from a reception side to temporarily stop data transmission of a transmission side. In addition, in the control in units of priority groups, priority flow control is performed by assigning the same priority to every piece of traffic within the same physical port. The priority flow control is defined in IEEE 802.1Qbb, and an object of the priority flow control is to secure quality of service (QoS). In the priority flow control, flow control is executed in independent priority.